An atomic absorption photometer includes an atomization unit which atomizes a sample. At the atomization unit, atomic vapor is generated due to atomization of a sample, and the atomic vapor is irradiated with a measuring beam from a light source. A light source which emits a bright line spectrum, such as a hollow cathode lamp (HCL), is used as the above light source. In a case where atomic vapor is irradiated with a measuring beam from such a light source, since light of a specific wavelength is absorbed in the atomic vapor, the sample can be analyzed by measuring absorbance of the light.
In an analysis of a sample using the atomic absorption photometer, for example, in a case where a large amount of mixtures such as salts are mixed in the sample, the mixtures may not dissociate completely even at high temperature, and a measuring beam from the light source may be absorbed by the mixture. As described, absorption may occur due to a factor other than absorption by a target element, and such absorption is referred to as background absorption (for example, see Patent Document 1 listed below).
In a case where background absorption occurs, since absorbance due to background absorption is added to absorbance due to atomic absorption of a target element, it is difficult to accurately measure absorbance due to atomic absorption. Therefore, in order to eliminate the influence of background absorption, background correction is performed by using the D2 lamp method, the Zeeman method, a self-reversal method (SR method), or the like.
In the D2 lamp method, background correction is performed, by irradiating atomic vapor generated at the atomization unit with a measuring beam for background measurement by using, for example, a D2 lamp (deuterium lamp). That is, in a case where background correction is performed by using the D2 lamp method, a light source which emits a continuous spectrum is used in addition to a light source which emits, for example, a bright line spectrum, calculation is performed by using spectra obtained by irradiating atomic vapor with measuring beams from the light sources, and thus background correction is performed.
In the Zeeman method, background correction is performed, by generating a magnetic field at the atomization unit from a magnetic field generation unit such as an electromagnet. That is, in a case where background correction is performed by using the Zeeman method, operation of the magnetic field generation unit is switched when atomic vapor is irradiated with a measuring beam from the light source which emits, for example, a bright line spectrum, calculation is performed by using the spectrum obtained at that time, and thus background correction is performed.
In the self-reversal method, background correction is performed by irradiating atomic vapor generated at the atomization unit with a measuring beam, for example, with an overcurrent. That is, in a case where background correction is performed by using the self-reversal method, a measuring beam is emitted for a fixed short time period with an overcurrent when atomic vapor is irradiated with the measuring beam from the light source which emits, for example, a bright line spectrum, calculation is performed by using the spectrum obtained at that time, and thus background correction is performed.